Accuracy of transmittance measurement of inspection machine for semitransparent defect and its detectability

As the wafer design rule is getting smaller, the size and transmittance of the defect on the reticle, especially for the semi-transparent defect, is one of the important factors to be controlled in mask shop. In order to minimize controversy for the accuracy of size and transmittance measurement, we need to define the detection and measurement ability of each inspection machine for the half-tone defect. In this work, we make semi-transparent defects with FIB repair tool, SEIKO, and treat this plate with NaOH. We first investigate the delectability of each inspection machine for the semi-transparent defects according to the size and transmittance increase and accuracy of size measuring tool supported in each inspection machine, KLA, lasertec and ORBOT. We verify the measurement result with CD SEM for the size and AIMS for the transmittance.